1. Field of the Invention
The present invention relates to processed starches for use in bakery foods to impart improved moldability to the dough and achieve outstanding effects in giving an improved texture to the food and ameliorating the deterioration of the food with time. The invention relates also to bakery foods utilizing the processed starch.
2. Description of the Prior Art
Foods available in recent years have generally become softer, and it is desired that bakery foods also have a soft or tender texture. Bakery foods undergo deterioration, usually becoming harder with lapse of time after baking and tasting undesirable due to a crumbly texture. The deterioration is thought attributable chiefly to the retrogradation of starch. This drawback is precluded to some extent with use of sugars, emulsifiers, thickeners, etc., but the result achieved still remains unsatisfactory.
To give a soft texture to bread or impart a tender agreeable texture to sponge cake and the like, emulsifiers such as glycerin fatty acid esters, propylene glycol fatty acid esters or sucrose fatty acid esters are used, whereas these emulsifiers have the problem that when used in an amount sufficient to achieve the desired effect, the emulsifier impairs the flavor and taste of the food. Although fats and oils in the form of an emulsion, such as condensed milk, are also used, they have difficulty in giving a constant quality to end products unless they are used in greatly limited conditions.
As a method of imparting an improved texture to bakery foods with use of starches, we have already applied a patent to substitute gluten and a processed starch which does not swell in cold water for a portion of wheat flour to obtain bread of soft texture (unexamined Japanese Patent Publication 87135-1991). However, this method has the drawback that the amount of substitution is as great as 10 to 20 wt % to result in an increased cost. Although cooked-up starch solutions are also used, they have the drawback of encountering difficulty in obtaining a end product of specified quality unless the starch is gelatinized under strict control. Such starches have another drawback in that if used in an amount sufficient to obtain the desired effect, the starch produces larger voids in the resulting crumb of bread. It has also been applied a patent to use pregelatinized starch which is prepared from untreated wheat flour, corn starch or potato starch (unexamined Japanese Patent Publication 175845-1984). Nevertheless, use of the pregelatinized starch is liable to make the dough sticky during processing, render the dough difficult to handle and afford bread which tends to be sticky and have a poor mouthfeel.
We have previously disclosed a process for preparing bread incorporating crosslinked pregelatinized starch which is 4.0 to 35 in cold water swelling power, having a soft texture and less susceptible to staling with time (Japanese Patent Application 209731-1990). This process produces a remarkable effect as contemplated but still has the problem of caving, i.e., shrinkage of baked bread which occurs on cooling, especially caving of the sides of loaves of bread.
Other modified starches are also proposed which are limited in swelling volume or swelling power. Unexamined Japanese Patent Publications 5700-1982 and 148554-1988 disclose a modified starch having a swelling volume of about 3 to 15 ml/g and a modified starch having a swelling power of 3.0 to 6.0, respectively. However, the swelling volume or power is a value determined at room temperature and does not involve the concept of swelling that occurs during heating in food production processes. The volume or degree of swelling resulting from actual heating is several times as great as the corresponding value at room temperature. These proposals are therefore different from the present invention in the concept of swelling and fail to produce the effect contemplated by the present invention.